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Conference on visual communications and image processing 2001

作者： Zhang, C Li, J Carnegie Mellon Univ Dept Elect & Comp Engn Pittsburgh PA 15213 USA

ISBN: (纸本)0819439886

In this paper, we describe a system for wandering in a realistic environment over the Internet. The environment is captured by the concentric mosaic, compressed via the reference block coder (RBC), and accessed and delivered over the Internet through the virtual media (Vmedia) access protocol. Capturing the environment through the concentric mosaic is easy. We mount a camera at the end of a level beam, and shoot images as the beam rotates. The huge dataset of the concentric mosaic is then compressed through the RBC, which is specifically designed for both high compression efficiency and just-in-time (JIT) rendering. Through the JIT rendering function, only a portion of the RBC biostream is accessed, decoded and rendered for each virtual view. A multimedia communication protocol - the Vmedia protocol, is then proposed to deliver the compressed concentric mosaic data over the Internet. Only the bitstream segments corresponding to the current view are streamed over the Internet. Moreover, the delivered bitstream segments are managed by a local Vmedia cache so that frequently used bitstream segments need not be streamed over the Internet repeatedly, and the Vmedia is able to handle a RBC bitstream larger than its memory capacity. A Vmedia concentric mosaic interactive browser is developed where the user can freely wander in a realistic environment, e.g., rotate around, walk forward/backward and sidestep, even under a tight bandwidth of 33.6 kbps.

关键词： virtual reality image based rendering (IBR) concentric mosaic reference block coder (RBC) virtual media (Vmedia) access protocol just-in-time (JIT) rendering interactive browsing cache

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Local bandwidth constrained fast inverse motion compensation for DCT-domain video transcoding

Local bandwidth constrained fast inverse motion compensation...

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IEEE International Conference on Acoustics, Speech, and Signal processing

作者： Liu, S Bovik, AC Laboratory for Image and Video Eng. Dept. of Elec. and Comp. Engineering The University of Texas at Austin Austin TX 78712-1084 United States

ISBN: (纸本)0780370414

DCT-based digital video coding standards such as MPEG and H.26x are becoming more widely adopted for multimedia applications. Since the standards differ in their format and syntax, video transcoding, where a pre-coded video bit-stream is converted from one format to another format, is of interest for purposes such as channel bandwidth adaptation and video composition. DCT-domain video transcoding is generally more efficient than spatial domain transcoding. However, since the data is organized block by block in the DCT-domain, inverse motion compensation becomes the bottleneck for DCT-domain methods. In this paper, we propose a novel local bandwidth constrained fast inverse motion compensation algorithm operating in the DCT-domain. Relative to Chang's algorithm [1], the proposed algorithm achieves computational improvement of 25% to 55% without visual degradation. A by-product of the proposed algorithm is a reduction of blocking artifacts in very low bit-rate compressed video sequences.

关键词： Motion compensation

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A distributed and adaptive signal processing approach to exploiting correlation in sensor networks

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Ad Hoc Networks 2004年第4期2卷 387-403页

作者： Chou, Jim Petrovic, Dragan Ramchandran, Kannan Department of EECS University of California at Berkeley Berkeley CA 94709 United States

We propose a novel approach to reducing energy consumption in sensor networks using a distributed adaptive signal processing framework and efficient algorithm. This work was supported in part by DARPA-F30602-00-2-0538, NSF-CCR-0219722 and Intel.1 While the topic of energy-aware routing to alleviate energy consumption in sensor networks has received attention recently [C. Toh, IEEE Commun. Mag. June (2001) 138;R. Shah, J. Rabaey, Proc. IEEE WCNC, March 2002], in this paper, we propose an orthogonal approach to complement previous methods. Specifically, we propose a distributed way of continuously exploiting existing correlations in sensor data based on adaptive signal processing and distributed source coding principles. Our approach enables sensor nodes to blindly compress their readings with respect to one another without the need for explicit and energy-expensive inter-sensor communication to effect this compression. Furthermore, the distributed algorithm used by each sensor node is extremely low in complexity and easy to implement (i.e., one modulo operation), while an adaptive filtering framework is used at the data gathering unit to continuously learn the relevant correlation structures in the sensor data. Applying the algorithm to testbed data resulted in energy savings of 10-65% for a multitude of sensor modalities. © 2003 Publishesd by Elsevier B.V.

关键词： Signal processing

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Enhancement of out-of-focused images using fusion-based PSF estimation and restoration

Enhancement of out-of-focused images using fusion-based PSF ...

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visual communications and image processing 2001

作者： Joon Shik Yoon Jeong Ho Shin Joon Ki Paik Department of Image Engineering Graduate Sch. Advanced Imaging Sci. Chung-Ang University 221 Huksuk-Dong Dongjak-Ku Seoul 156-756 Korea Republic of

In this paper, we propose an enhancement algorithm of out-of-focused images using fusion-based Point-spread-function (PSF) estimation and restoration. The proposed algorithm can make in-focused image by using only digital image processing techniques, and it requires neither infrared light / ultrasound nor focusing lens assembly operated by electrically powered movement of focusing lens. In order to increase accuracy in estimating the PSF of the defocus image, the proposed algorithm finds true and linear edges by using Canny edge detector, which is optimal edge detector and has good localization, estimates the step response across the edge for each pixel, computes the one-dimensional step response by averaging the step responses, estimates the two-dimensional PSF from the averaged step response, and then provides in-focused image by image restoration filter based on the estimated PSF. Finally, we execute fusion process, which can enhance the quality of the fused image by fusing restored images. There is a limit of the amount of out-of-focus, which can be recovered by the proposed algorithm. Moreover, the proposed algorithm is operating under assumption that an input image contains at least one piece-wise linear boundary between an object and background. In spite of above-mentioned limitations, the proposed algorithm can make acceptable quality of focused image by using only digital image processing.

关键词： image enhancement

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Long transition analysis for post shot boundary detection

Long transition analysis for post shot boundary detection

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visual communications and image processing 2001

作者： Wei Jyh Heng Ngan, K.N. Visual Communications Research Group Department of Electrical Engineering University of Western Australia Nedlands WA 6907 Australia

With the introduction of the standard in video indexing, research in shot boundary detection has recently become popular. While new solutions for long transition detection have recently emerged, there is not much literature that focuses on what to do with the frames within the transition when they are detected. After the approximate position of the long transition is detected, the raw sequence cannot be used for segmentation and indexing due to the special effects incorporated. Here, a technique aims at extracting extra information from the transition after the existence of a long transition is confirmed. This technique consists of four stages, namely, shot boundary refinement, shot type determination, frame reconstruction for soft transition and pixel classification for hard transition. This paper gives the overview as well as performance of each stage. This technique allows detected transitions to be analysed without human intervention.

关键词： Edge detection

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Shot Boundary Detection Using Convolutional Neural Networks

Shot Boundary Detection Using Convolutional Neural Networks

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30th IEEE Conference on visual communications and image processing (VCIP)

作者： Xu, Jingwei Song, Li Xie, Rong Shanghai Jiao Tong Univ Inst Image Commun & Network Engn Shanghai Peoples R China Cooperat Medianet Innovat Ctr Shanghai Peoples R China

ISBN: (纸本)9781509053162

Video shot boundary detection (SBD) is necessary for further video analysis like video retrieval and annotation. Great efforts have been made to develop SBD algorithms for speed and accuracy. Most works implement frame histogram as features to measure similarity for detection. However, when changes between consecutive shot boundaries are small and backgrounds of them are highly similar, most state-of-the-art methods miss these boundaries thus cannot achieve high accuracy of detection. In this paper we propose a novel SBD framework with Convolutional Neural Networks (CNNs). Firstly we adopt a candidate segment selection method to locate the positions of shot boundaries coarsely using adaptive thresholds and eliminate most non-boundary frames. Then CNN is implemented to extract representative features of frames in candidate segments. Finally cut and gradual transitions can be obtained by using a novel pattern-matching method based on a new similarity strategy. Experiments on TRECVID 2001 test data demonstrate that the proposed scheme outperforms the state-of-the-art methods and achieves high accuracy of detection.

关键词： Shot boundary detection adaptive thresholds convolutional neural networks cut transition detection gradual transition detection pattern matching

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Object segmentation using skin color and motion information

Object segmentation using skin color and motion information

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visual communications and image processing 2001

作者： Eui Yoon Chung Ho Keun Lee Hyung Suk Kim Yeong Ho Ha Sch. of Electronic/Electrical Eng. Kyungpook National Univ. Taegu 702-701 Korea Republic of

This paper presents an effective object segmentation method for object-oriented coding. The process is composed of facial region detection using skin color and changed region detection using motion information. The image is then segmented between moving objects and background using motion estimation. The facial regions are detected using skin color, the data for which is obtained from the u, v image. This data is then used as a threshold to segment the facial region. The image is also segmented into changed regions using motion information. After combining these results, the final image is segmented between moving objects and background. This method is more efficient due to two factors, color and motion. Experimental results show that the proposed method can significantly improve the image quality.

关键词： image segmentation

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Simultaneous digital focusing and motion blur removal using segmentation-based adaptive regularization

Simultaneous digital focusing and motion blur removal using ...

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visual communications and image processing 2001

作者： Sang Kyu Kang Min Ji Hong Joon Ki Paik Depart. of Image Engineering Graduate Sch. Advanced Imaging Sci. Chung-Ang University 221 Huksuk-Dong Dongjak-Ku Seoul 156-756 Korea Republic of

Recently, many image processing systems are required to offer high-quality images. For example, when we use a surveillance system with a digital camcorder and a digital video recorder, it is highly probable that the acquired image suffers from various image degradation, such as motion blur and out-of-focus blur. With such degradation, we cannot obtain important information. This is mainly caused by limited performance of image formation system. In this work, we investigate the causes of focus blur and motion blur. With the simultaneous formulation of the corresponding degradation, we propose a spatially adaptive regularization algorithm for restoring out-of-focus and motion blurred images. Accordingly, we present a method to estimate blur parameters and a segmentation method for spatially adaptive processing.

关键词： image segmentation

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Artifact free signal denoising with wavelets

Artifact free signal denoising with wavelets

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IEEE International Conference on Acoustics, Speech, and Signal processing

作者： Durand, S Froment, J CMLA Ecole Normale Super Cachan F-94235 Cachan France

ISBN: (纸本)0780370414

Recent years have seen the development of signal denoising algorithms based on wavelet transform. It has been shown that thresholding the wavelet coefficients of a noisy signal allows to restore the smoothness of the original signal. However, wavelet denoising suffers of a main drawback : around discontinuities the reconstructed signal is smoothed, exhibiting pseudo-Gibbs phenomenon. We consider the problem of denoising piecewise smooth signals with sharp discontinuities. We propose to apply a traditional wavelet denoising method and to restore the denoised signal using a total variation minimization approach. This second step allows to remove the Gibbs phenomena and therefore to restore sharp discontinuities, while the other structures are preserved. The main innovation of our algorithm is to constrain the total variation minimization by the knowledge of the remaining wavelet coefficients. In this way, we make sure that the restoration process does not deteriorate the information that has been considered as significant in the denoising step. With this approach we substantially improve the performance of classical wavelet denoising algorithms, both in terms of SNR and in terms of visual artifacts.

关键词： Signal processing

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Scalable internet video streaming with differential JPEG-2000 video codec and content-aware rate control

Scalable internet video streaming with differential JPEG-200...

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visual communications and image processing 2001

作者： Zhao, L. Jong Won Kim Kuo, C.-C.J. Integrated Media Systems Center Dept. of Elec. Engineering-Systems University of Southern California Los Angeles CA 90089-2564 United States

A scalable video streaming system that includes video preprocessing, differential JPEG-2000 (DJ2K) video codec, and content-aware rate control is proposed. The proposed streaming solution tackles the problem of maintaining smooth video quality even when there is a significant change in the source content or the transmission bandwidth. The wavelet-based JPEG-2000 video codec provides temporal, spatial and SNR scalabilities. A rate controller, which is separated from the encoder, can deal with diverse demands of a wide variety of users and various traffic conditions in a heterogeneous network by leveraging offerred scalabilities and content-awareness. Simulations are conducted to demonstrate various advantages of the proposed solution.

关键词： Video signal processing

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